The Seeds of the Revolution
The late 1970s also saw the introduction of the first low-pressure steel 104s. For cave divers, in particular, these were a godsend. With a little creative filling, double 104s could increase your penetration range by 50 percent over aluminum 80s.
But there was a problem. Steel 104s were incredibly negative. Even when wearing a neoprene dry suit, a diver in double 104s could require as much as 40 pounds or more of additional lift to be neutrally buoyant at the surface. The largest jacket style BCs could not provide this kind of lift — nor did they fit snugly enough to keep tanks from shifting around too much.
The solution to this problem was first identified by a cave diving instructor named Rory Dickens in the late 1970s. In the then-current edition of the NSS-CDS Cave Diving Manual, Rory published illustrations of what he called “the ideal compensator,” which would surround heavy doubles in such a manner as to provide adequate lift and balance. You’d recognize these drawings if you could see them; they look exactly like today’s modern technical diving BCs.
By the mid-1980s, it was possible for cave and wreck divers to buy large, back-inflation BCs from Dive Rite. These were used almost exclusively with double cylinders and you never saw recreational divers using them.
By the early 1990s, things started to change. Technical diving came out of the closet. Nitrox stopped being “Devil Gas” and started being the thing that every diver was supposed to do. Then, in 1995, Dive Rite introduced the Transpac, the first BC that crossed the line between technical and recreational diving.
The effect was profound. In no time at all, manufacturers were falling all over themselves sewing tech-style D-rings on recreational BCs — and making certain their product lines had at least one back-inflation BC in them, for those divers who wanted the “tech diver look.”
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